Abstract:

There is plentiful genetic variation in turfgrass cultivars of ryegrass, apparently exceeding that found in forage ryegrasses. The fact that this variation has been exploited in breeding programmes is evidenced by the rapid improvement in turfgrass performance in characters such as shoot density, fine texture and improved colour. However, little or no advance has been made in improving both biotic and abiotic stress tolerance of ryegrass cultivars. Although there is potential to improve stress tolerance/adaptability of our cultivars using the existing pool of improved germplasm, there is no reason to be complacent and a search for further variation in wild germplasm will extend possibilities for improvement. But there is some evidence that genetic erosion of our germplasm resource is occurring through the plant breeding, agricultural and industrialisation activities of man. Ex situ conservation, in gene banks, is therefore an essential additional resource and, if managed correctly, will help prevent genetic erosion of our ryegrass germplasm. To use germplasm collections effectively, it is necessary to characterise plant populations, a task that is difficult and time-consuming. Now that DNA markers can be generated quickly and in large numbers it is much easier to genetically characterise plant material held in our gene banks. Associating these markers with important traits for use in plant breeding programmes is more difficult and until now has required the setting up of mapping populations derived from single crosses between individual plants. The techniques of association and linkage disequilibrium (LD) mapping used in mapping human diseases has the potential to closely map traits in natural ryegrass populations and may prove to be a useful tool for introgressing characters from wild germplasm resources (including Festuca spp.) into elite breeding lines.